1. Field of the Invention
The present invention relates to semiconductor cleaning apparatuses, and more particularly, to a wafer guide for use in a semiconductor cleaning apparatus, which is capable of preventing a wafer breakage and process error.
2. Description of the Related Art
Semiconductor devices are becoming larger in size and higher in density. As a result, impurity particles or micro-pollution particles of a wafer generated in etching or ion implantation, diffusion processes, etc., considerably influence a production yield. Accordingly a cleaning process for eliminating various pollution materials of wafers produced in semiconductor manufacturing processes is essential to the manufacturing of semiconductor devices.
Conventionally, a wet cleaning process may be used to remove micro-pollution particles such as metal impurities and organic materials from wafers. The wet cleaning process may remove pollution materials by soaking wafers in baths filled with ultra-pure chemicals such as sulfuric acid, hydrochloric acid, and ammonium, etc.
Wafers are generally transferred by a robot chuck. For example, about 50 sheets of wafers grouped as a batch unit from a cassette are chucked and transferred to respective baths using the robot chuck. The grouped wafers are chucked and transferred as a batch unit to a wafer guide adapted inside the respective baths. Specifically, the wafers chucked in batch from a cassette are transferred to a wafer guide that is adapted within a bath using the robot chuck, and a cleaning process is performed in the wafer guide using the chemicals. Then the wafers are transferred to a subsequent process using the robot chuck.
Slots are formed in respective support arms to support wafers of the robot chuck and the wafer guide. The slots are formed with substantially the same interval and in the same number, and each wafer sheet is inserted into each slot, respectively. That is, slots of the same number as the batch unit are formed in the support arm of the robot chuck and the wafer guide to support wafers in the batch unit.
In the robot chuck, support arms are adapted at both sides in parallel with each other so as to individually and simultaneously rotate pivotally on one side thereof in mutually opposite directions. Thus, lower end parts of both support arms become mutually near or far in distance during an open/close operation.
In the robot chuck, support arms of both sides first perform an open operation so as to approach the wafers, and then the support arms of both sides perform a close operation so as to chuck the wafers therein. While in the state of having chucked the wafers therein, the support arms move to approach a wafer guide or cassette. Subsequently, the wafers are transferred in a batch unit to the wafer guide or cassette by again performing an open operation of both support arms.
However, when the robot chuck moves to the wafer guide where previously cleaned wafers are stacked, the support arms of the robot chuck and the wafer guide must be located so that slots are placed on the same vertical lines. For example, when the robot chuck deviates from a predetermined loading position, the slots of the robot chuck and the wafer guide are not precisely matched to one another. Thus, in a chucking step of unloading wafers from the wafer guide by the robot chuck, a portion of the wafers may not be exactly inserted into slots of the robot chuck, and the wafers abnormally chucked in the robot chuck may be broken. The wafers may break in a wafer guide side by a strong chucking pressure of the robot chuck.
Further, for example, when the process continues in the state where the broken wafer remains intact in the wafer guide, wafers that are subsequently loaded into the wafer guide by the robot chuck are transferred to the wafer guide. As a result, additional wafers cannot be sufficiently inserted into slots due to the broken wafer parts remaining in the wafer guide. This causes a relatively severe process defect.
When the process is interrupted owing to such wafer breakage and process defect, much time is consumed to recover the interrupted process. In addition, defective products are created, thereby causing a decrease in productivity.